/*
 * Copyright 2002-2006 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.mock.web;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;

import javax.el.ELContext;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.el.ExpressionEvaluator;
import javax.servlet.jsp.el.VariableResolver;

import org.springframework.util.Assert;

/**
 * Mock implementation of the {@link javax.servlet.jsp.PageContext} interface.
 * 
 * <p>
 * Used for testing the web framework; only necessary for testing applications
 * when testing custom JSP tags.
 * 
 * <p>
 * Note: Expects initialization via the constructor rather than via the
 * <code>PageContext.initialize</code> method. Does not support writing to a
 * JspWriter, request dispatching, and <code>handlePageException</code> calls.
 * 
 * @author Juergen Hoeller
 * @since 1.0.2
 */
public class MockPageContext extends PageContext {

	private final ServletContext servletContext;

	private final HttpServletRequest request;

	private final HttpServletResponse response;

	private final ServletConfig servletConfig;

	private final Hashtable attributes = new Hashtable();

	/**
	 * Create new MockPageContext with a default {@link MockServletContext},
	 * {@link MockHttpServletRequest}, {@link MockHttpServletResponse},
	 * {@link MockServletConfig}.
	 */
	public MockPageContext() {
		this(null, null, null, null);
	}

	/**
	 * Create new MockPageContext with a default {@link MockHttpServletRequest},
	 * {@link MockHttpServletResponse}, {@link MockServletConfig}.
	 * 
	 * @param servletContext
	 *            the ServletContext that the JSP page runs in (only necessary
	 *            when actually accessing the ServletContext)
	 */
	public MockPageContext(ServletContext servletContext) {
		this(servletContext, null, null, null);
	}

	/**
	 * Create new MockPageContext with a MockHttpServletResponse,
	 * MockServletConfig.
	 * 
	 * @param servletContext
	 *            the ServletContext that the JSP page runs in
	 * @param request
	 *            the current HttpServletRequest (only necessary when actually
	 *            accessing the request)
	 */
	public MockPageContext(ServletContext servletContext,
			HttpServletRequest request) {
		this(servletContext, request, null, null);
	}

	/**
	 * Create new MockPageContext with a MockServletConfig.
	 * 
	 * @param servletContext
	 *            the ServletContext that the JSP page runs in
	 * @param request
	 *            the current HttpServletRequest
	 * @param response
	 *            the current HttpServletResponse (only necessary when actually
	 *            writing to the response)
	 */
	public MockPageContext(ServletContext servletContext,
			HttpServletRequest request, HttpServletResponse response) {
		this(servletContext, request, response, null);
	}

	/**
	 * Create new MockServletConfig.
	 * 
	 * @param servletContext
	 *            the ServletContext that the JSP page runs in
	 * @param request
	 *            the current HttpServletRequest
	 * @param response
	 *            the current HttpServletResponse
	 * @param servletConfig
	 *            the ServletConfig (hardly ever accessed from within a tag)
	 */
	public MockPageContext(ServletContext servletContext,
			HttpServletRequest request, HttpServletResponse response,
			ServletConfig servletConfig) {

		this.servletContext = (servletContext != null ? servletContext
				: new MockServletContext());
		this.request = (request != null ? request : new MockHttpServletRequest(
				servletContext));
		this.response = (response != null ? response
				: new MockHttpServletResponse());
		this.servletConfig = (servletConfig != null ? servletConfig
				: new MockServletConfig(servletContext));
	}

	public void initialize(Servlet servlet, ServletRequest request,
			ServletResponse response, String errorPageURL,
			boolean needsSession, int bufferSize, boolean autoFlush) {

		throw new UnsupportedOperationException("Use appropriate constructor");
	}

	public void release() {
	}

	public void setAttribute(String name, Object value) {
		Assert.notNull(name, "Attribute name must not be null");
		if (value != null) {
			this.attributes.put(name, value);
		} else {
			this.attributes.remove(name);
		}
	}

	public void setAttribute(String name, Object value, int scope) {
		Assert.notNull(name, "Attribute name must not be null");
		switch (scope) {
		case PAGE_SCOPE:
			setAttribute(name, value);
			break;
		case REQUEST_SCOPE:
			this.request.setAttribute(name, value);
			break;
		case SESSION_SCOPE:
			this.request.getSession().setAttribute(name, value);
			break;
		case APPLICATION_SCOPE:
			this.servletContext.setAttribute(name, value);
			break;
		default:
			throw new IllegalArgumentException("Invalid scope: " + scope);
		}
	}

	public Object getAttribute(String name) {
		Assert.notNull(name, "Attribute name must not be null");
		return this.attributes.get(name);
	}

	public Object getAttribute(String name, int scope) {
		Assert.notNull(name, "Attribute name must not be null");
		switch (scope) {
		case PAGE_SCOPE:
			return getAttribute(name);
		case REQUEST_SCOPE:
			return this.request.getAttribute(name);
		case SESSION_SCOPE:
			HttpSession session = this.request.getSession(false);
			return (session != null ? session.getAttribute(name) : null);
		case APPLICATION_SCOPE:
			return this.servletContext.getAttribute(name);
		default:
			throw new IllegalArgumentException("Invalid scope: " + scope);
		}
	}

	public Object findAttribute(String name) {
		Object value = getAttribute(name);
		if (value == null) {
			value = getAttribute(name, REQUEST_SCOPE);
			if (value == null) {
				value = getAttribute(name, SESSION_SCOPE);
				if (value == null) {
					value = getAttribute(name, APPLICATION_SCOPE);
				}
			}
		}
		return value;
	}

	public void removeAttribute(String name) {
		Assert.notNull(name, "Attribute name must not be null");
		this.removeAttribute(name, PageContext.PAGE_SCOPE);
		this.removeAttribute(name, PageContext.REQUEST_SCOPE);
		this.removeAttribute(name, PageContext.SESSION_SCOPE);
		this.removeAttribute(name, PageContext.APPLICATION_SCOPE);
	}

	public void removeAttribute(String name, int scope) {
		Assert.notNull(name, "Attribute name must not be null");
		switch (scope) {
		case PAGE_SCOPE:
			this.attributes.remove(name);
			break;
		case REQUEST_SCOPE:
			this.request.removeAttribute(name);
			break;
		case SESSION_SCOPE:
			this.request.getSession().removeAttribute(name);
			break;
		case APPLICATION_SCOPE:
			this.servletContext.removeAttribute(name);
			break;
		default:
			throw new IllegalArgumentException("Invalid scope: " + scope);
		}
	}

	public int getAttributesScope(String name) {
		if (getAttribute(name) != null) {
			return PAGE_SCOPE;
		} else if (getAttribute(name, REQUEST_SCOPE) != null) {
			return REQUEST_SCOPE;
		} else if (getAttribute(name, SESSION_SCOPE) != null) {
			return SESSION_SCOPE;
		} else if (getAttribute(name, APPLICATION_SCOPE) != null) {
			return APPLICATION_SCOPE;
		} else {
			return 0;
		}
	}

	public Enumeration getAttributeNames() {
		return this.attributes.keys();
	}

	public Enumeration getAttributeNamesInScope(int scope) {
		switch (scope) {
		case PAGE_SCOPE:
			return getAttributeNames();
		case REQUEST_SCOPE:
			return this.request.getAttributeNames();
		case SESSION_SCOPE:
			HttpSession session = this.request.getSession(false);
			return (session != null ? session.getAttributeNames() : null);
		case APPLICATION_SCOPE:
			return this.servletContext.getAttributeNames();
		default:
			throw new IllegalArgumentException("Invalid scope: " + scope);
		}
	}

	public JspWriter getOut() {
		throw new UnsupportedOperationException("getOut");
	}

	public ExpressionEvaluator getExpressionEvaluator() {
		return new MockExpressionEvaluator(this);
	}

	public VariableResolver getVariableResolver() {
		return null;
	}

	public HttpSession getSession() {
		return this.request.getSession();
	}

	public Object getPage() {
		throw new UnsupportedOperationException("getPage");
	}

	public ServletRequest getRequest() {
		return request;
	}

	public ServletResponse getResponse() {
		return response;
	}

	public Exception getException() {
		throw new UnsupportedOperationException("getException");
	}

	public ServletConfig getServletConfig() {
		return servletConfig;
	}

	public ServletContext getServletContext() {
		return servletContext;
	}

	public void forward(String url) throws ServletException, IOException {
		throw new UnsupportedOperationException("forward");
	}

	public void include(String url) throws ServletException, IOException {
		throw new UnsupportedOperationException("include");
	}

	public void include(String url, boolean flush) throws ServletException,
			IOException {
		throw new UnsupportedOperationException("include");
	}

	public void handlePageException(Exception ex) throws ServletException,
			IOException {
		throw new UnsupportedOperationException("handlePageException");
	}

	public void handlePageException(Throwable ex) throws ServletException,
			IOException {
		throw new UnsupportedOperationException("handlePageException");
	}
}
